As a young man, the Hull FC coach, Peter Sharp, had plenty of fun playing amateur rugby league in London but he cannot have enjoyed yesterday in the capital. His struggling side lost a 16-0 lead to succumb to a defeat that leaves them with a huge uphill task to reach the Super League play-offs and puts Sharp under even more pressure.

"We are physically and mentally fragile at the moment, down in confidence," said Sharp. "There's a lot of rugby left but the only way is up."

Only two minutes had elapsed when the Great Britain cap Chris Melling dropped Adam Dykes' up and under, allowing Richard Whiting to touch down for the visitors, Craig Hall converting. It was typical of a scrappy, tense first half, peppered by penalties, handling errors and sideways running by both teams.

The Airlie Birds were certainly defending like a team who knew they had to win to remain in the play-off hunt. At the other end of the field, Tommy Lee took advantage after Rikki Sheriffe failed to deal with a high kick, Hall slotting over his second conversion to make it 12-0 to Hull.

The men in black and white should have added to their lead only for wing Todd Byrne to drop the ball over the line under no pressure whatsoever. On 33 minutes they did score again. Hull were given a dubious penalty for interference and they worked the ball right for Danny Washbrook to stroll over.

Quins gave themselves a lifeline with a try on the half-time hooter by Tony Clubb after some hard running by Gareth Haggerty, Henry Paul making it 6-16. When Hull dropped the ball from the second-half kick-off and stood still, Julien Rinaldi collected and raced under the sticks to score.

The revitalised home side started breaking the Hull line, but it was the visitors who scored next when Kirk Yeaman raced 75 metres to go over.

Quins half-back Scott Hill had looked rusty in the first half on his return from injury but he showed why he was once Australia's stand-off by creating two tries in two minutes for Michael Worrincy and Melling. Clubb soon powered over for another try on the left wing, Paul's two kicks putting Quins 28-20 ahead.

When Melling and Whiting both hacked at air rather than the ball – Whiting taken off with a badly broken leg as a result – Matt Sing touched down to give Hull hope. But deep into injury time, Melling juggled Chad Randall's pass before scoring to seal Quins' first win for a month.